JPH08290675A - Thermal transfer sheet and image forming method - Google Patents

Abstract

PURPOSE: To obtain a thermal transfer sheet having a good dot quality and imparting an image approximating to a printed matter and obtain an image forming method using this sheet. CONSTITUTION: A thermal transfer sheet is provided with an ink layer containing 30-70wt.% pigment and 25-65wt.% amorphous organic high-molecular polymer having a softening point in the temperature range of 40-150 deg.C and ranging 0.2-1.0 μm in layer thickness. The ink layer is made of a material having no self-supporting properties in the form of a sheet having a film thickness of 200μm and a size of 3 by 5cm. An image-receiving sheet is overlapped on the ink layer of the thermal transfer sheet. On the back surface of the thermal transfer sheet, a thermal head is pressed, or a laser light modulated by digital signals is emitted (or a laser light modulated by digital signals is emitted in an ablation method). In this manner, a transfer image formed with an area gradation of a 1.0 or more optical reflection density is formed on the image- receiving sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive transfer sheet having an ink layer and an image forming method using the heat-sensitive transfer sheet, and in particular, an ink layer is formed on an image-receiving sheet by using a thermal head printer or laser light. The present invention relates to a heat-sensitive transfer sheet useful for forming a high quality multi-tone color image (full color image) by image-wise transfer by area gradation recording, and an image forming method using the same.

[0002]

2. Description of the Related Art Conventionally, as a thermal transfer recording system for forming a color image using a thermal head printer, a sublimation type dye transfer system and a thermal fusion type transfer system are known. In the sublimation dye transfer method, a transfer sheet having a transfer layer consisting of a sublimation dye and a binder provided on a support is superposed on an image receiving sheet, and heat is applied imagewise by a thermal head from the back side of the transfer sheet support. , A sublimation dye is sublimated and transferred to an image receiving sheet to form an image on the image receiving sheet. In this method, it is also possible to form a color image (full color image) by using a transfer sheet having sublimation dyes of yellow, magenta and cyan.

However, the sublimation dye method has the following drawbacks. (1) The gradation expression of an image mainly uses density gradation (controls the kind or amount of dye), and is suitable for the purpose of obtaining an image of gradation similar to that of a photograph. However, for example, it is not suitable for a color proof used in the printing field where gradation is expressed only by area gradation (multi-value recording). (2) Since image formation uses dye sublimation, the edge sharpness of the finished image is unlikely to be sufficient,
Further, the solid density of the thin line tends to be lower than that of the thick line.
These are serious drawbacks regarding the quality of character images. (3) Since the durability of the image is inferior, its use is limited to the fields requiring heat resistance and light resistance. (4) Since the thermal recording sensitivity is lower than that of the thermal fusion type transfer system, it is not suitable as a high speed recording material using a high resolution thermal head which is expected to be put to practical use in the future. (5) The transfer material is more expensive than the heat-melt transfer material.

On the other hand, the heat-melt transfer method prepares a heat-sensitive transfer sheet in which a heat-meltable ink transfer layer composed of a coloring material such as a pigment or a dye and a binder such as wax is provided on a support. This is a system in which an image is formed by superposing it on an image receiving sheet and applying imagewise heat from the back side of the support of the transfer sheet with a thermal head to melt the transfer layer and transfer and fuse it onto the image receiving sheet. Compared with sublimation dye transfer method, heat fusion transfer method has advantages such as high heat sensitivity, inexpensive material, and excellent light resistance of image, but has the following drawbacks. have. That is, a major drawback of the thermal fusion transfer system is that the quality of the color image is inferior to that of the sublimation dye transfer system. This is because the general recording method by this method is not the gradation reproduction by the density gradation recording but the binary recording. Of course, in the thermal fusion transfer method, various proposals have been made to improve the ink transfer layer for achieving density gradation recording for the purpose of forming a multi-gradation color image without using binary recording. It was However, the basic idea behind these improvements is to use the property that the binder in the ink layer melts and the viscosity decreases due to heating by the thermal head, and as a result, the adhesive force to the image receiving sheet increases and transfer is performed. By controlling the temperature rise of the ink layer to control the cohesive failure inside the ink layer, and thus controlling the transfer amount of the ink layer, that is, to perform multi-gradation recording by softening the gamma characteristic of thermal transfer recording. There is. However, even if such a method is used, the thermal fusion transfer method is inferior in terms of multi-gradation to the sublimation dye transfer method. Also, it is generally said that the thermal fusion transfer method is inferior in terms of reproducibility of image density such as fine lines.

Further, in the hot-melt transfer method, since a crystalline wax having a low melting point is usually used as a binder for the ink layer, the resolution of the ink may be lowered due to the blurring of the ink in the heat-sensitive transfer sheet at the time of thermal printing. It also tends to occur, and the fixing strength of the transferred image tends to be insufficient, which is also a problem. Furthermore, the crystalline waxes have the drawback that it is difficult to obtain a transparent image due to the light scattering of the crystalline phase. This is a major drawback when forming a full-color image as an overlapping image such as a yellow image, a magenta image, and a cyan image. Further, even when the pigment ratio with respect to the total amount of the ink layer is high, such a decrease in transparency of the full-color image is likely to occur. Therefore, as described in Japanese Examined Patent Publication No. 63-65029, the colorant is usually used in an amount of 20 parts by weight or less with respect to 100 parts by weight of the total amount of the ink layer. To do.

Various proposals have been made in order to improve the color reproduction of a color image of the thermal fusion transfer system. For example,
JP-A-61-244592 (Japanese Patent Publication No. 5-1307)
No. 2), in order to improve transparency, fixed image strength and the like while maintaining continuous gradation (density gradation), 65% by weight or more of an amorphous polymer and a releasable substance are disclosed. A thermal transfer sheet having a thermal ink layer made of a colorant (dye or pigment) has been proposed. In this publication, amorphous polymer is 6
When it is less than 5% by weight, the transparency of the heat-sensitive transfer sheet is remarkably deteriorated and good color reproducibility cannot be obtained. To obtain particularly good transparency, the content of the amorphous polymer is 70%.
It is stated that weight percent is required. The colorant contained in the heat-sensitive ink layer for maintaining transparency is 20
The weight% is the upper limit, and in order to obtain the image density and image strength required for practical use, the layer thickness of the thermal ink layer is usually 1 μm.
.About.20 .mu.m is preferable, and 3 .mu.m is adopted as the layer thickness of the thermal ink layer in the examples. In this publication, the heat-sensitive transfer sheet (heat-sensitive recording material) of the invention is disclosed.
Indicates that it can be used for binary recording and multilevel recording. However, according to the study by the present inventor, continuous tone recording using the thermal transfer sheet described in the above publication cannot be said to be sufficiently satisfactory in terms of continuity and stability of density tone. On the other hand, in a multi-value transfer image or a binary transfer image obtained by using the above-mentioned thermal transfer sheet,
It is difficult to obtain a sufficient density gradation, the transparency (particularly the transparency of a full-color image) is not sufficient, and the edge sharpness cannot be said to be sufficiently satisfactory.

On the other hand, in the thermal transfer system, multi-value recording using area gradation (that is, image formation in which recording is performed using dots having different areas, VDS: variable dot system) Methods for obtaining full-color images are already known. It is also known that it is desirable that the heat-sensitive transfer sheet for use in multi-valued recording utilizing this area gradation has the following characteristics. (1) Each color has a predetermined image density. Particularly, in terms of proof use, the finally obtained cyan, magenta and yellow image densities (retransferred image densities on a white support) have optical reflection densities of at least 1.0, respectively.
It is necessary to be above, and it is desirable that it is 1.2 or more, particularly 1.4 or more. It is said that it is preferable that the black content is 1.5 or more. Therefore, the heat-sensitive transfer sheet is desired to be capable of forming such a high-density image. (2) Excellent gradation reproducibility. (3) Those capable of forming a dot shape having excellent edge sharpness of a line or point image. (4) The transferred ink layer has high transparency. (5) High sensitivity. (6) Printing The image transferred to the actual paper (usually a white support such as coated paper) shows high similarity to the printed matter in terms of texture, glossiness of the image, and the like.

In recent years, the technical progress of the thermal head printer as a means for supplying heat to the heat-sensitive transfer sheet has been remarkable. Further, as a printing method capable of increasing the resolution of the thermal head itself and enabling multi-gradation recording in area gradation, there are disclosed in Japanese Patent Application Laid-Open Nos. 4-19163 and 5-155057. The sub-scanning division method and the heat concentration type method described in "Annual Meeting of the Electrophotographic Society 1992/7/6 Proceedings" have been proposed.

As a method for forming a transfer image using a heat-sensitive transfer sheet, a method using a laser beam, that is, a digital image forming method has been developed in recent years. In this method, an image receiving sheet is superposed on the ink layer of the thermal transfer sheet, and a laser beam modulated by a digital signal is irradiated from the back of the thermal transfer sheet to form a transfer image on the image receiving sheet (this transfer image Can also be retransferred onto another sheet). In this case, in order to convert the light energy of the laser beam into heat energy with high efficiency, it is also common to provide a photothermal conversion layer composed of a carbon black layer, a metal thin film or the like between the ink layer and the support. Has been done to. Further, in order to further improve the image quality of the transferred image (in particular, the density uniformity of the image and the edge sharpness), the ink layer is locally peeled (separated) without the melt transfer.
A so-called ablation method is also used in which the image is transferred to an image receiving sheet.

[0010]

The applicant of the present invention invented a heat-sensitive transfer sheet particularly suitable for the multi-gradation transfer system by area gradation as described above, and has already filed a patent application (Japanese Patent Application No. 5-2).
No. 63695 application). By using the heat-sensitive transfer sheet of the above patent application, multi-tone high-quality color images and monochrome images can be obtained by a pigment transfer method of area gradation only, and color proof in the printing field as well as normal image formation, By utilizing the durability of the original copy or pigment, it has become possible to develop into the card field, outdoor display field, meter display field, etc.

However, there is room for further improvement in the heat-sensitive transfer sheet having excellent performance as described above. For example, the edge sharpness of the transferred image, the quality of dots formed (dot shape, minimum limit of reproducible limit). It was found that further improvement is desirable in terms of halftone dot%) and gradation reproducibility. In particular, in the case of proof use, etc., the retransfer image finally obtained by using the above-mentioned thermal transfer sheet (formed by retransferring the transfer image formed on the image receiving sheet to another printing main paper). It was also found that it is desirable that the image) have a high degree of similarity with the proof of the sample created from the lith original.

Therefore, an object of the present invention is to provide a heat-sensitive transfer sheet which is suitable for a multi-gradation transfer system and which has excellent characteristics satisfying the above requirements (1) to (6). Particularly, in the present invention, it is an object of the present invention to provide a thermal transfer sheet which has an excellent dot quality and gives an image similar to a printed matter, and an image forming method using the same.

[0013]

The present inventor has conducted earnest studies for a heat-sensitive transfer sheet having good performance as described above, and as a result, compared with the conventional sublimation dye heat-sensitive transfer method and melt transfer method. , A method that should be called the thermal adhesive thin film peeling method of the present invention, that is, a method of peeling and transferring a thin film ink layer containing a pigment at a high concentration, and by forming a heat sensitive ink layer brittle, The inventors have found that the image quality (particularly, dot quality and gradation reproducibility) can be improved, and have reached the present invention.

The present invention has a pigment and a softening point of 40 ° C to 1
It has an ink layer containing 30 to 70% by weight and 25 to 65% by weight of an amorphous organic high-molecular polymer in a temperature range of 50 ° C. and having a layer thickness in a range of 0.2 μm to 1.0 μm. In addition, the ink layer and the constituent material of the ink layer have a film thickness of 20.
The heat-sensitive transfer sheet is made of a material that does not have self-supporting properties when it is formed into a sheet having a size of 0 μm, 3 cm × 5 cm.

Further, in the present invention, an image receiving sheet is superposed on the ink layer of the above heat sensitive transfer sheet, a thermal head is pressed against the back surface of the heat sensitive transfer sheet, and an area having an optical reflection density of 1.0 or more on the image receiving sheet. There is also an image forming method including forming a transfer image composed of gradations.

Further, in the present invention, an image receiving sheet is superposed on the ink layer of the heat sensitive transfer sheet, and a thermal head is pressed against the back surface of the heat sensitive transfer sheet to form a transfer image composed of area gradation on the image receiving sheet. Then, the transferred image on the image-receiving sheet is re-transferred onto a separately prepared white support, and an optical reflection density of 1.0 or more is formed on the white support. There is also an image forming method including forming a transfer image.

Further, according to the present invention, an image receiving sheet is superposed on the ink layer of the above-mentioned thermal transfer sheet, and a laser beam modulated by a digital signal is irradiated from the back surface of the thermal transfer sheet, and the optical reflection density on the image receiving sheet. There is also an image forming method including forming a transfer image having an area gradation of 1.0 or more.

In the present invention, an image receiving sheet is superposed on the ink layer of the above-mentioned thermal transfer sheet, a laser beam modulated by a digital signal is irradiated from the back surface of the thermal transfer sheet, and the image receiving sheet is subjected to the ablation method. There is also an image forming method including forming a transfer image having an optical reflection density of 1.0 or more in area gradation.

The present invention preferably has the following aspects. (1) The particle size of 70% by weight or more of the pigment in the ink layer is in the range of 0.1 to 1.0 μm. (2) Amorphous organic polymer is 10 to 90% by weight
(More preferably 20 to 60% by weight) of a mixture of amorphous chlorinated polyolefin resin or vinyl chloride / vinyl acetate copolymer and the balance of other amorphous organic polymer. (3) The amorphous organic high-molecular polymer is a mixture of 10 to 90% by weight of an amorphous chlorinated polyolefin resin or vinyl chloride / vinyl acetate copolymer and 90 to 10% by weight of polyvinyl butyral. (4) The chlorinated polyolefin resin is a chlorinated polypropylene resin or a chlorinated polyethylene resin. (5) The layer thickness of the ink layer is in the range of 0.2 to 0.6 μm.

The heat-sensitive transfer sheet of the present invention will be described below. As described above, the heat-sensitive transfer sheet of the present invention contains a pigment and an amorphous organic high-molecular polymer having a softening point in the temperature range of 40 ° C. to 150 ° C. in an amount of 30 to 70% by weight, respectively.
And 25 to 65% by weight, and the film thickness is 0.2 μm to 1.0
It has an ink layer in the range of μm, and the constituent material of this ink layer is a material that does not have self-supporting property when a sheet having a film thickness of 200 μm, 3 cm × 5 cm is formed. It is what Here, having no self-supporting property means that when the sheet having the above-mentioned size is sandwiched between the corners of the sheet and broken down, the sheet breaks and the shape thereof is not maintained. That is, the ink layer of the heat-sensitive transfer sheet of the present invention has extremely high brittleness. Therefore, by using the heat-sensitive transfer sheet having such an ink layer, the dots of the transferred image are well removed and the dot shape becomes very sharp. The heat-sensitive transfer sheet of the present invention is advantageously used for forming a multi-tone image (particularly a full-color image) by area-wise tone by heat-sensitive transfer, but it can also be used for binary recording. Of course.

The heat-sensitive transfer sheet of the present invention has an ink layer containing a pigment and an amorphous organic polymer on a support. For the ink layer having high brittleness as described above, specifically, a chlorinated polyolefin resin or a vinyl chloride / vinyl acetate copolymer should be used as an amorphous organic high molecular polymer which is a constituent component of the ink layer. Can be achieved by

As the support of the heat-sensitive transfer sheet, various supports known as the support of the conventional heat-transfer sheet for melt transfer or sublimation transfer are used. Mold release treatment applied, thickness 5
A polyester film of about μm is particularly preferable.

As the pigment contained in the ink layer of the heat-sensitive transfer sheet of the present invention, various known pigments can be used, for example, carbon black, azo type, phthalocyanine type, quinacridone type, thioindigo type, anthraquinone type, isoindo type. Examples include pigments such as linone. These can be used in combination of two or more kinds, and a known dye may be added for adjusting the hue. In the heat-sensitive transfer sheet of the present invention, the content of the pigment in the ink layer is 30% by weight to 70% by weight (more preferably 30% by weight to 50% by weight) in order to obtain a predetermined concentration in a thin film. If the pigment ratio is less than 30% by weight, it becomes difficult to obtain the concentration with the above-mentioned predetermined film thickness. Further, in the present invention, the particle size of the pigment is preferably such that 70% by weight or more of the pigment is in the range of 0.1 to 1.0 μm. When the particle size is large, the transparency of the overlapping portion of each color during color reproducibility is likely to be impaired, and it may be difficult to satisfy both of the relationship between the layer thickness and the density.

The amorphous organic high molecular weight polymer having a softening point of 40 ° C. to 150 ° C. contained in the ink layer of the heat-sensitive transfer sheet of the present invention is, as described above, 10 to 90% by weight (preferably, abundance). 20 to 60% by weight) is preferably composed of a chlorinated polyolefin resin or a vinyl chloride / vinyl acetate copolymer. The chlorinated polyophine resin usable in the present invention has, for example, a chlorine content of 10% by weight.
Above (preferably 30% by weight or more) chlorinated polypropylene resin (specifically, Super Clone 106H (chlorine content: 66% by weight or more), manufactured by Nippon Paper Industries Co., Ltd.), chlorinated polyethylene resin (specifically Eraslen 404
B (chlorine content: 40% by weight or more), Showa Denko KK
Manufactured by Nippon Paper Industries Co., Ltd., Super Klon HE-905 (chlorine content: 66% by weight or more). Specific examples of the vinyl chloride / vinyl acetate copolymer include MPR-TAL, MPR-TMF (manufactured by Nisshin Chemical Co., Ltd.), and Denka vinyl # 1000A (manufactured by Denki Kagaku Kogyo KK). it can. The ratio (weight) of both components of the vinyl chloride / vinyl acetate copolymer is not particularly limited, but the former: the latter is preferably in the range of 60:40 to 95: 5. These may be used alone or in combination of two or more.

In the present invention, examples of the amorphous organic polymer which can be used in combination with the chlorine polyolefin resin or the vinyl chloride-vinyl acetate copolymer include butyral resin, polyamide resin, polyethyleneimine resin and sulfonamide resin. , Polyester polyol resin, petroleum resin, styrene, α-methylstyrene, 2-methylstyrene, chlorostyrene, vinylbenzoic acid, sodium vinylbenzene sulfonate, styrene and its derivatives such as aminostyrene, homopolymers and copolymers of substitution products,
Methacrylic acid esters such as methyl methacrylate, ethyl methacrylate and hydroxyethyl methacrylate, acrylic acid esters such as methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, α-ethylhexyl acrylate and dienes such as acrylic acid, butadiene, isodiene and isoprene. , Acrylonitrile, vinyl ethers, maleic acid and maleic acid esters, maleic anhydride, and cinnamic acid, vinyl monomers such as homopolymers or copolymers of other monomers. Two or more kinds of these resins may be mixed and used. Of these, butyral resin and styrene / maleic acid half ester resin are preferable from the viewpoint of dispersibility. Butyral resin is particularly preferable. The softening point of these resins is selected in the range of 40 ° C to 150 ° C. 150 ° C
If the temperature exceeds 40 ° C., the thermal recording sensitivity tends to be low. A specific example of butyral resin is Denka butyral # 20.
00-L (degree of polymerization: about 300), # 4000-1 (degree of polymerization: about 920) (above, manufactured by Denki Kagaku Kogyo Co., Ltd.), S-REC BX-10 (Tg: 74 ° C., degree of polymerization: 80, Acetalization degree: 69 mol%), S-REC BL-S (T
g: 61 ° C., ethatric viscosity: 12 cps, Sekisui Chemical Co., Ltd. can be mentioned.

In the heat-sensitive transfer sheet of the present invention, the content of the amorphous organic polymer in the ink layer is 25 to 65.
% By weight (preferably 30 to 50% by weight).

In the ink layer of the heat-sensitive transfer sheet of the present invention,
In order to improve the releasability of the ink layer from the support and the thermal sensitivity at the time of thermal printing, various releasing agents and softening agents are added to the ink layer.
It is also possible to add it in an amount of 0% by weight or less. Specifically, for example, palmitic acid, higher fatty acids such as stearic acid, fatty acid metal salts such as zinc stearate, fatty acid esters or partially saponified products thereof, fatty acid derivatives, higher alcohols, ether derivatives of polyhydric alcohols, and the like,
Waxes such as paraffin wax, carnauba wax, montan wax, beeswax, wood wax, candelilla wax, etc., and viscosity average molecular weights of about 1,000 to 10,0.
Polyolefins such as low molecular weight polyethylene of about 00, polypropylene, polybutylene, etc., or olefins,
Low molecular weight copolymers of α-olefins with organic acids such as maleic anhydride, acrylic acid, methacrylic acid, etc., low molecular weight copolymers, low molecular weight oxidized polyolefins, halogenated polyolefins, lauryl methacrylate, stearyl methacrylate, etc. Long chain alkyl side chains Of methacrylic acid ester, acrylic acid ester or perfluoro group-containing acrylic acid ester, methacrylic acid ester alone or copolymers with vinyl monomers such as styrenes, low polydimethylsiloxane, polydiphenylsiloxane, etc. Molecular weight silicone resins and silicone-modified organic substances, etc., and also cationic surfactants such as ammonium salts and pyridinium salts having long-chain aliphatic groups, or anions, nonionic surfactants, perfluoro, which also have long-chain aliphatic groups. System surface activity And the like can be given. These can be used alone or in combination of two or more.

Regarding the dispersion of the above-mentioned pigment in the amorphous organic polymer, various dispersion methods used in the field of paints such as ball milling with the addition of a suitable solvent can be applied. A releasing agent or the like is added to the obtained dispersion to prepare a coating material, and the coating material thus prepared can be applied onto a support by a known method to form an ink layer.

The ink layer of the heat-sensitive transfer sheet of the present invention has a layer thickness of 0.2 μm-1.0 μm (preferably 0.2-m).
0.6 μm). When the thickness of the ink layer is thicker than 1.0 μm, the shadow portion is easily crushed or the highlight portion is easily skipped in the area gradation reproducibility, resulting in poor gradation reproducibility. On the other hand, if the layer thickness is less than 0.2 μm, it becomes difficult to obtain the desired concentration.

The ink layer of the heat-sensitive transfer sheet of the present invention is mainly composed of a pigment and an amorphous organic high-molecular polymer, and has a higher pigment ratio than the conventional wax-melting type. The hourly viscosity does not fall as low as 10 ² to 10 ³ cps and is at least higher than 10 ⁴ cps at a temperature of 150 ° C. Therefore, the image forming method by thermal transfer using the thermal transfer sheet of the present invention is a thin film peeling development type image utilizing thermal adhesiveness to the image receiving sheet or thermal adhesiveness between ink layers in the case of color image formation. It can also be said to be formation. This, combined with the effect of thinning the ink layer, makes it possible to reproduce a wide range of gradations from the shadow portion to the highlight portion while maintaining high resolution, and to improve edge sharpness.
It enables transfer of images of 00%. This makes it possible to reproduce, for example, a small character of 4 points and evenness in the density of solid areas.

As the image receiving sheet used in the image forming method of the present invention, thermosoftening synthetic paper or US Pat.
No. 482625, No. 4766053, and No. 49.
It is possible to use the image-receiving sheet technology provided with a heat-adhesive layer containing an organic high-molecular polymer described in each specification of No. 33258 and the like. As a support for the image-receiving sheet provided with a heat-adhesive layer containing at least an organic polymer, paper or a plastic film such as a polyester film, a polycarbonate film, a polypropylene film or a polyvinyl chloride film can be used. When used for proofing, a transfer image formed on a plastic film may be retransferred to the printing main paper to form an image on the same paper as the printing main paper to form an image.

Next, the image forming method of the present invention will be described. The image forming method of the present invention can be carried out by using the thermal transfer sheet having the above structure and the image receiving sheet as described above, utilizing a thermal head printer or a laser beam. First, in the case of using a thermal head printer, an image receiving sheet as described above is superposed on the ink layer of the thermal transfer sheet of the present invention, the thermal head is pressed against the back surface of the thermal transfer sheet, and after printing, It is carried out by peeling the support of the transfer sheet from the image receiving sheet, whereby a transfer image having an area gradation with an optical reflection density of 1.0 or more can be formed on the image receiving sheet. Further, the transfer image on the image-receiving sheet obtained as described above is further overlaid on a white support, which is a separately prepared printing main sheet, and pressure and heat treatment is performed in this state to re-image on the white support. A transfer image can be obtained. This makes it possible to form a retransfer image having an optical reflection density of 1.0 or more in area gradation. The above-mentioned image forming method can be specifically carried out by using a method conventionally known as an image forming method using a thermal head printer using a thermal transfer sheet.

When the image forming method of the present invention is carried out by using a laser beam, it can be carried out by irradiating a laser beam imagewise instead of the thermal head in the above image forming method. As an image forming method using a laser beam, for example, an image forming method utilizing so-called “ablation” disclosed in US Pat. No. 5,352,562 and JP-A-6-219052 can be used. Specifically, the image forming method described in JP-A-6-219052 is a layer (photothermal conversion layer) that absorbs laser light and converts it into heat between the support and the ink layer (image forming layer). ) And a layer containing a heat-sensitive material that generates gas by the action of heat generated in the light-heat conversion layer (heat-sensitive peeling layer) (or heat-sensitive peeling when the light-heat converting layer contains the heat-sensitive material). A heat-sensitive transfer sheet provided with a photothermal conversion layer also having the function of a layer) and an image receiving sheet laminated on the ink layer, and the conversion of the conversion layer due to the temperature rise of the photothermal conversion layer by irradiation of laser light. Utilizes a phenomenon in which ablation occurs due to alteration, melting, etc., the heat-sensitive peeling layer is partially decomposed and vaporized, the binding force between the ink layer and the photothermal conversion layer is weakened, and the ink layer in that area is transferred to the image receiving sheet. It is a thing. By using the above-mentioned ablation method, it is also possible to form a transfer image having an optical reflection density of 1.0 or more in area gradation on the image receiving sheet. Further, by using the actual printing paper as the image receiving sheet, it is possible to form a transfer image formed on the actual printing paper with an area gradation of which the optical reflection density is 1.0 or more. In the image forming method using the above method, the ink layer is melted by the heat generated by the absorption of the laser light, and the area is melt-transferred to the image receiving sheet, so that the transfer image is formed on the image receiving sheet. It can also be formed.

The photothermal conversion layer and the heat-sensitive peeling layer provided on the heat-sensitive transfer sheet used in the ablation method will be described below. The ink layer is the one according to the present invention. In general, the photothermal conversion layer has a basic structure including a dye (pigment or the like) capable of absorbing laser light and a binder. Examples of dyes (pigments, etc.) that can be used are black pigments such as carbon black, pigments of macrocyclic compounds having absorption in the visible to near infrared region such as phthalocyanine and naphthalocyanine, and high density laser recording of optical disks. Examples include organic dyes (cyanine dyes such as indolenine dyes, anthraquinone dyes, azulene dyes, phthalocyanine dyes) used as laser absorbing materials, and organometallic compound dyes such as dithiol nickel complexes. The photothermal conversion layer is preferably as thin as possible in order to increase the recording sensitivity. Therefore, it is desirable to use a cyanine dye or a phthalocyanine dye that exhibits a large absorption coefficient in the laser light wavelength region.

The material of the binder of the light-heat conversion layer is not particularly limited, but for example, acrylic acid, methacrylic acid,
Acrylic acid esters, homopolymers or copolymers of acrylic acid type monomers such as methacrylic acid esters, methyl cellulose, ethyl cellulose, cellulose type polymers such as cellulose acetate, polystyrene, vinyl chloride-vinyl acetate copolymer, polyvinylpyrrolidone, polyvinyl Butyral, copolymers of vinyl polymers and vinyl compounds such as polyvinyl alcohol, condensation polymers such as polyester and polyamide, rubber-based thermoplastic polymers such as butadiene-styrene copolymer,
Examples thereof include polymers obtained by polymerizing and crosslinking a photopolymerizable or thermopolymerizable compound such as an epoxy compound.

When the photothermal conversion layer comprises a dye (dye or pigment) and a binder, the weight ratio is 1: 5 to 10: 1.
(Dye: Binder) is preferred, especially 1: 3
It is preferably set to 3: 1. When the amount of the binder is too small, the cohesive force of the light-heat conversion layer is reduced, and when the formed image is transferred to the image receiving sheet, it is easily transferred together.
This will cause color mixing in the image. Further, if the amount of the binder is too large, it is necessary to increase the layer thickness of the photothermal conversion layer in order to achieve a constant light absorption rate, which tends to cause a decrease in sensitivity. The layer thickness of the photothermal conversion layer comprising the above dye and binder is generally 0.05 to 2 μm, preferably 0.1 to 1 μm. Further, the photothermal conversion layer preferably exhibits a light absorption rate of 70% or more at the wavelength of the laser light used for optical recording.

The heat-sensitive release layer is a layer containing a heat-sensitive material. As such a heat-sensitive material, a compound (polymer or low-molecular compound) that itself decomposes or deteriorates by heat to generate gas, or a characteristic of the material is to absorb or adsorb a considerable amount of easily vaporizable gas such as water. Compounds (polymers or low molecular weight compounds) that are used can be used. Note that they can be used in combination. Examples of the polymer that decomposes or deteriorates due to heat to generate gas include self-oxidizing polymers such as nitrocellulose, chlorinated polyolefin, chlorinated rubber, polychlorinated rubber, polyvinyl chloride, halogen such as polyvinylidene chloride. Containing polymer, acrylic polymer such as polyisobutyl methacrylate that adsorbs volatile compounds such as water, cellulose ester such as ethyl cellulose that adsorbs volatile compounds such as water, volatile compounds such as water adsorbed Examples thereof include natural polymer compounds such as gelatin. Examples of the low molecular weight compound that decomposes or deteriorates by heat to generate a gas include a compound such as a diazo compound or an azide compound that generates a gas by exothermic decomposition. As described above, the decomposition and deterioration of the heat-sensitive material due to heat,
It is preferable that it occurs at 280 ° C or lower, particularly 230 ° C.
It preferably occurs in the following.

When a low molecular weight compound is used as the heat sensitive material in the heat sensitive release layer, it is desirable to combine it with a binder. In this case, the binder may be a polymer which itself decomposes or denatures by heat to generate a gas, or a normal polymer binder having no such property. When the heat-sensitive low molecular weight compound and the binder are used in combination, the weight ratio of the former to the latter is 0.02: 1 to 3: 1 and particularly 0.05: 1 to 2: 1.
It is preferably in the range of. It is desirable that the heat-sensitive peeling layer covers the light-heat conversion layer almost entirely, and the thickness thereof is generally 0.03 to 1 μm, and particularly 0.0.
It is preferably in the range of 5 to 0.5 μm.

[0039]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited thereto. [Example 1] (Preparation of heat-sensitive transfer sheet) Three kinds of pigment / amorphous organic polymer polymer dispersions A, B, and C for ink layers having the following compositions were prepared. Amorphous organic polymer Polyvinyl butyral resin 9.6 parts by weight (Denka Butyral # 2000-L, manufactured by Denki Kagaku Kogyo Co., Ltd.) 2.4 parts by weight chlorinated polypropylene resin (Super Clone 106H, Nippon Paper Industries Co., Ltd. )) Pigment ABC Cyan pigment (C.I.P.B. 15: 4) 12 parts by weight --- Magenta pigment (C.I.PR. 57: 1) -12 parts by weight-Yellow pigment (C.I. PY. 14) -12 parts by weight Dispersion aid 0.8 parts by weight (Solspers S-20000, manufactured by ICI Japan Co., Ltd.) Solvent n-propyl alcohol 33 parts by weight Methyl ethyl ketone 77 parts by weight

0.24 parts by weight of N-hydroxyethyl-12-hydroxystearic acid amide, a surfactant (MegaFac F-177, large) are added to 10 parts by weight of each of the dispersions A, B and C. Made by Nippon Ink Chemical Co., Ltd.
0.01 parts by weight and 60 parts by weight of n-propyl alcohol were added to prepare coating solutions A, B, and C, and a 5 μm-thick polyester film (manufactured by Teijin Ltd.) having a release treatment on its back surface was applied by a spin coater (whirler). And the coating liquid A was 0.36 μm, the coating liquid B was 0.38 μm, and the coating liquid C was 0.42 μm.
A cyan thermal transfer sheet, a magenta thermal transfer sheet, and a yellow thermal transfer sheet were prepared (Sample 1). Figure 1 shows the particle size distribution of the cyan pigment used.
2, the particle size distribution of the magenta pigment is shown in FIG. 2, and the particle size distribution of the yellow pigment is shown in FIG.

[Example 2] to [Example 6] The amorphous organic high molecular polymer used in the preparation of the heat-sensitive transfer sheet of Example 1 was changed in the same manner as in Table 1 below,
A heat-sensitive transfer sheet corresponding to each was prepared (Sample 2).

[Comparative Example 1] The same procedure as in the above Example was carried out except that only 12 parts by weight of polyvinyl butyral was used as the amorphous organic polymer used in the preparation of the heat-sensitive transfer sheet of Example 1. A thermal transfer sheet was prepared (Comparative Control Sample 1).

The particle size of the pigment in each dispersion when preparing the heat-sensitive transfer sheets of Examples 2 to 6 and Comparative Example 1 was as follows:
The same distribution as in Example 1 was shown. The constitution of the amorphous organic high-molecular polymer used in each of the obtained heat-sensitive transfer sheets (Samples 1 to 6 and Control Sample 1) is shown in Table 1 below.

[0044]

[Table 1] Table 1 ──────────────────────────────────── Amorphous organic polymer (Use amount: parts by weight) Chlorinated polypropylene PVC / vinyl acetate copolymer Polyvinyl Trade name Use amount Trade name Use amount Butyral ─────────────────────── ───────────── Sample 1 Super Clone 2.4 None 9.6 106H Sample 2 Super Clone 6.0 None 6.0 6.0 H Sample 3 Super Clone 9.8 None 2.2 106H Sample 4 None MPR-TMF 2.4 9.6 Sample 5 None MPR-TMF 6.0 6.0 Sample 6 None MPR-TMF 9.6 2.4 ──────────────── ───────────────────── Control sample 1 None 12.0 ──────────────────────────────────── Vinyl chloride / vinyl acetate copolymer: MPR -TMF (manufactured by Nisshin Chemical Co., Ltd.) (Vinyl chloride: vinyl acetate: other = 90: 7: 3)

With respect to each of the heat-sensitive transfer sheets obtained above, the self-supporting property of the ink layer was evaluated by the following method. (Preparation of sample) A coating solution having the following composition was applied on a stainless steel plate and dried (25 ° C, 2 days, then 8
A coating film on a sheet having a dry film thickness of 200 μm was formed at 0 ° C. for 12 hours. Next, a sheet having a size of 3 cm × 5 cm was cut out from this coating film to obtain a sample. (Composition of coating liquid) A pigment / amorphous organic polymer polymer dispersion liquid for an ink layer having the following composition was prepared. Amorphous organic polymer Polyvinyl butyral resin 9.6 parts by weight (Denka Butyral # 2000-L, manufactured by Denki Kagaku Kogyo Co., Ltd.) 2.4 parts by weight chlorinated polypropylene resin (Super Clone 106H, Nippon Paper Industries Co., Ltd. ) Pigment Cyan pigment (C.I.P.B. 15: 4) 12 parts by weight Dispersion aid 0.8 parts by weight (Solspers S-2000, manufactured by ICI Japan Co., Ltd.) Solvent n-propyl alcohol 33 parts by weight Methyl ethyl ketone 77 parts by weight

With respect to 10 parts by weight of the above dispersion, 0.24 parts by weight of N-hydroxyethyl-12-hydroxystearic acid amide and a surfactant (MegaFac F-17) were used.
7, 0.01 part by weight of Dainippon Ink and Chemicals, Inc. and 1 part by weight of n-propyl alcohol were added to prepare a coating solution. Further, instead of the cyan pigment, a coating solution using a magenta pigment (C.I.PR. 57: 1) or a yellow pigment (C.I.PY.14) was similarly prepared and used as a sample. (Evaluation of Self-Supporting Property) It was confirmed whether or not the sheet was broken when the corner portion of the sheet obtained above was sandwiched with tweezers and was suspended (or was about to be suspended).
Table 2 shows the results.

(Preparation of Image Receiving Sheet) An image receiving first layer forming coating solution and an image receiving second layer forming coating solution having the following compositions were prepared. Coating solution for image receiving first layer PVC / vinyl acetate copolymer 25 parts by weight (MPR-TSL, manufactured by Nissin Chemical Co., Ltd.) 12 parts by weight dibutyloctyl phthalate (DOP, manufactured by Daihachi Chemical Co., Ltd.) Surfactant 4 parts by weight (Megafuck F-177, manufactured by Dainippon Ink and Chemicals, Inc.) Solvent (methyl ethyl ketone) 75 parts by weight

Coating liquid for image receiving second layer: 16 parts by weight of polyvinyl butyral (Denka Butyral # 2000-L, manufactured by Denki Kagaku Kogyo Co., Ltd.) 4 parts by weight of N, N-dimethylacrylamide / butyl acrylate copolymer Surfactant 0 .5 parts by weight (MegaFac F-177, manufactured by Dainippon Ink and Chemicals, Inc.) solvent (n-propyl alcohol) 200 parts by weight

On a 100-μm thick polyethylene terephthalate (PET) film support, the coating solution for the first image receiving layer was applied at 300 rpm using a spin coater and dried in an oven at 100 ° C. for 2 minutes. . The thickness of the obtained first image receiving layer was 20 μm. Further, the coating solution for the image receiving second layer was applied onto the image receiving first layer at 200 rpm using a spin coater, and dried in an oven at 100 ° C. for 2 minutes. The thickness of the obtained image receiving second layer was 2 μm.

[Image formation and evaluation using thermal head] Using the heat-sensitive transfer sheet and the image-receiving sheet obtained above,
The image forming method was carried out in the following procedure. First, a cyan thermal transfer sheet and an image receiving sheet were superposed on each other, and printing was performed by a thermal head recording device by a sub-scanning division method. This principle is a system in which a 75 μm × 50 μm head is turned on and off in the direction of 50 μm with a minute feed of 3 μm to perform multi-step modulation of only area gradation. The polyester film of the cyan heat-sensitive transfer sheet was peeled off to form an image having only area gradation on the image receiving sheet. Then, a magenta heat-sensitive transfer sheet is superposed on the image-receiving sheet on which the cyan image is formed, aligned and printed in the same manner, and the polyester film of the transfer sheet is peeled off to form a magenta image on the image-receiving sheet. did. Further, in the same manner, a yellow image was formed, and a color image (full color image) consisting only of area gradation was formed on the image receiving sheet.

Next, the image-receiving sheet on which the color image is formed is laid on the art paper, and the pressure is set to 4.5 kg / cm ² , and the pressure is set to 125.
After passing through a heat roller at 0 ° C. and a speed of 450 mm / sec, the polyester film of the image receiving sheet was peeled off, and the image receiving second layer having an ink image was transferred onto art paper. The reflection density of each single color in the obtained color image was as follows. Optical density (solid) Cyan 1.53 Magenta 1.43 Yellow 1.58

With respect to the obtained color image, the dot quality (shape, minimum dot mesh%) was evaluated as follows. The dot shape was shown by relative comparison by visual evaluation of 10 people according to the following evaluation criteria. The minimum dot net% was evaluated by measuring the dot% at the minimum reproducible limit using a Macbeth densitometer RD-918 (manufactured by Macbeth). A chemical proof (color art, Fuji Photo Film Co., Ltd.) was created from the squirrel document to approximate the printed matter of the obtained color image.
Evaluation). Table 2 shows the results.

[0053]

[Table 2] Table 2 ──────────────────────────────────── Ink layer dot quality Self-supporting property Shape Minimum dot network% Printed material similarity ───────────────────────────────────── Sample 1 None BB 4% BB sample 2 none AA 4% BB sample 3 none AA 3% AA sample 4 none BB 5% BB sample 5 none BB 4% BB sample 6 none AA 3% BB ─────────────── ────────────────────── Control sample 1 Yes DD 9% CC ──────────────────── ──────────────── Evaluation was performed by the following relative evaluation. However, the color image obtained using the comparative sample 1 was evaluated based on the following criteria (the dot shape was based on DD, and the printed matter similarity was based on CC). AA: Very good compared to the control. BB: Good compared with the comparative control.

From the results of Table 2 above, by using the heat-sensitive transfer sheet according to the present invention in which the ink layer is formed extremely brittle, the dot quality is improved and a transferred image having good printed matter approximation can be obtained. .

Example 7 As shown below, various image recording and transfer sheets (a variety of image recording transfer sheets were prepared by changing the amorphous high molecular polymer constituting the image forming layer (ink layer) as shown in Table 3 below. Thermal transfer sheet: Samples 7 to 12) were prepared. In addition, an image-receiving sheet for this was prepared, and the image-receiving layer side of the image-receiving sheet was superposed on the image-forming layer of the image-recording transfer sheet to form a laminate. Then, this laminate was irradiated with laser light by the following method to form a transfer image on the image receiving sheet. Also, as a comparative control sample,
Polyvinyl butyral 1 as an amorphous organic polymer
An image was formed by the same method as the one prepared by using only 2 parts by weight (Comparative Control Sample 2). The presence or absence of self-supporting property of the ink layer of each of the obtained heat-sensitive transfer sheets was evaluated by the same method as described above. The results are shown in Table 4.

(1) Preparation of Image Recording Transfer Sheet (Thermal Transfer Sheet) 1) Preparation of Photothermal Conversion Layer Forming Coating Liquid The following components are mixed with stirring with a stirrer to prepare a photothermal conversion layer forming coating liquid. did.

Coating liquid composition 0.3 g of the following infrared absorbing cyanine dye

[0058]

Embedded image

5% aqueous solution of polyvinyl alcohol (Poval, type 205, manufactured by Kuraray Co., Ltd.) 6 g Isopropyl Alur 5 g Ion-exchanged water 20 g Infrared absorbing dye (IR-820, manufactured by Nippon Kayaku Co., Ltd.) 1.7 g Polyamic acid Varnish (PAA-A, manufactured by Mitsui Toatsu Chemicals, Inc.) 13 g 1-methoxy-2-propanol 60 g Methyl ethyl ketone 88 g Surfactant (Megafuck F-177, manufactured by Dainippon Ink and Chemicals, Inc.) 0.05 g

2) Formation of a photothermal conversion layer on the surface of a support A styrene / butadiene copolymer undercoat layer (thickness: 0.5 μm) and a gelatin undercoat layer (on a surface of a polyethylene terephthalate film having a thickness of 75 μm) Thickness 0.1μ
and m) were formed in this order to prepare a support. Next, the above coating solution was applied onto the undercoat layer of this support by using a spin coater (Whorer), and then the coated product was dried in an oven at 100 ° C. for 2 minutes to give a coating on the support. And photothermal conversion layer (thickness 0.2 μm: measured value by stylus type film thickness meter, wavelength 830
An absorbance of 1.4) was formed.

3) Preparation of coating solution for forming heat-sensitive release layer The following components were mixed with a stirrer under stirring to prepare a coating solution for forming heat-sensitive release layer.

Composition of coating solution Nitrocellulose (Type HIG120, manufactured by Asahi Kasei Co., Ltd.) 1.3 g Methyl ethyl ketone 26 g Propylene glycol monomethyl ether acetate 40 g Toluene 92 g Surfactant (MegaFac F-177, manufactured by Dainippon Ink and Chemicals, Inc.) ) 0.01 g

4) Formation of a heat-sensitive peeling layer on the surface of the photothermal conversion layer The above coating solution was applied to the surface of the photothermal conversion layer provided on the above-mentioned support using a whaler, and then the coated product was heated to 100 ° C.
In the oven for 2 minutes, and a heat-sensitive release layer (thickness 0.1 μm: the same coating solution was applied to a hard sheet flat surface under the same conditions on the support and dried under the same conditions) to obtain a layer. (Measured by a stylus type film thickness meter).

5) Preparation of coating liquid for forming magenta image forming layer Each of the following components was applied to a paint shaker (Toyo Seiki Co., Ltd.).
Dispersion) for 2 hours to prepare a magenta pigment dispersion mother liquor. Then, the obtained dispersion mother liquor was diluted with n-propyl alcohol and measured with a particle size measuring device (laser light scattering method). The particle size distribution of the pigment was 70% by weight or more in the range of 180 to 300 nm. There was Pigment dispersion mother liquor composition Amorphous organic high molecular polymer 12.6 g Coloring material (magenta pigment, CI PR.57: 1) 18 g Dispersion aid (Solspers S-20000, manufactured by ICI Japan Co., Ltd.) 8g n-Propyl alcohol 110g Glass beads 100g

The following components were mixed with a stirrer with stirring to prepare a magenta image forming layer forming coating solution. Coating liquid composition: Pigment dispersion mother liquor 6 g n-Propyl alcohol 60 g Surfactant (MegaFac F-177, Dainippon Ink and Chemicals, Inc.) 0.01 g

6) Formation of a magenta image forming layer on the surface of the heat-sensitive peeling layer After coating the above-mentioned coating solution on the surface of the heat-sensitive peeling layer using a whaler, the coated product was dried in an oven at 100 ° C.
After being dried for a minute, a magenta image forming layer (thickness 0.3 μm: the same coating solution was applied to a hard sheet flat surface under the same conditions and dried under the same conditions) by a stylus method. The value measured by the film thickness meter) was formed. The optical density of the obtained image forming layer was 0.7 (measurement value with a green filter and a Macbeth densitometer). Through the above steps, an image recording / transferring sheet is prepared in which a photothermal conversion layer surface, a heat-sensitive peeling layer, and a magenta image forming layer having a large number of stearic acid amide crystals dispersed on the surface are laminated in this order on a support. did.

(2) Preparation of image-receiving sheet 1) Preparation of coating liquid for forming first image-receiving layer The following components were mixed with stirring with a stirrer to prepare a coating liquid for forming first image-receiving layer.

Composition of coating liquid Polyvinyl chloride (Zeon 25, manufactured by Nippon Zeon Co., Ltd.) 9 g Surfactant (Megafuck F-177P, manufactured by Dainippon Ink and Chemicals, Inc.) 0.1 g Methyl ethyl ketone 130 g Toluene 35 g Cyclohexanone 20 g Dimethylformamide 20g

2) Formation of the first image-receiving layer on the surface of the support: The above coating solution was applied on one surface of the support (a polyethylene terephthalate film having a thickness of 75 μm) using a whaler, and the coated product was heated to 100 ° C. And dried in the oven for 2 minutes to form a first image-receiving layer (thickness 1 μm) on the support.

3) Preparation of Second Image Receiving Layer Forming Coating Liquid The following components were mixed with stirring with a stirrer to prepare a second image receiving layer forming coating liquid.

Composition of coating liquid Methyl methacrylate / ethyl acrylate / methacrylic acid copolymer (Dianal BR-77, manufactured by Mitsubishi Rayon Co., Ltd.) 17 g Alkyl acrylate / alkyl methacrylate copolymer (Dianal BR-64, Mitsubishi Rayon ( 17 g pentaerythritol tetraacrylate (A-TMMT, manufactured by Shin Nakamura Chemical Co., Ltd.) 22 g Surfactant (Megafuck F-177P, manufactured by Dainippon Ink and Chemicals, Inc.) 0.4 g Methyl ethyl ketone 100 g Hydroquinone monomethyl Ether 0.05 g 2,2-dimethoxy-2-phenylacetophenone (photopolymerization initiator) 1.5 g 4) Second image-receiving layer formation on the surface of the first image-receiving layer The above-mentioned on the surface of the first image-receiving layer on the support. After applying the coating liquid of w And dried for 2 minutes at 100 ° C. in an oven, first image receiving layer on the support (thickness 26
μm). Through the above steps, on the support,
An image receiving sheet in which two image receiving layers were laminated was prepared.

(3) Preparation of Laminate for Image Forming The image recording transfer sheet and the image receiving sheet prepared as described above were allowed to stand at room temperature for one day and then placed on the magenta image forming layer of the image recording transfer sheet. , The image receiving layer side of the image receiving sheet is overlaid, and in this state, the surface temperature is 70 ° C. and the pressure is 4.
They were passed through a 5 kg / cm ² heat roller at a speed of 200 cm / sec to integrate them, thereby forming a laminate. In addition,
The temperature reached by each of the image recording transfer sheet and the image receiving sheet when passing through the heat roller was measured by a thermocouple and was about 50 ° C.

(4) Mounting of Image Forming Laminate on Image Recording Forming Apparatus The laminate obtained above was left at room temperature for about 10 minutes to be sufficiently cooled. Next, the laminated body is wound around a rotary drum provided with suction holes for vacuum suction so that the image receiving sheet surface side is in contact with the drum surface, and the inside of the drum is evacuated to form a drum. It was fixed on the surface.

(5) Image Recording on Image Forming Laminate A semiconductor laser beam having a wavelength of 830 nm is externally applied to the surface of the image forming laminate on the drum by rotating the drum.
A laser image (a sub-scan) is formed on the surface of the photothermal conversion layer so as to form a spot having a diameter of 7 μm and moved in a direction perpendicular to the rotation direction (main scanning direction) of the rotary drum (sub scanning). Streak) was recorded. The laser irradiation conditions are as follows. Laser power: 110 mW Main scanning speed: 10 m / sec Sub-scanning pitch (sub-scanning amount per rotation): 5 μm

(6) Formation of Transfer Image When the above-mentioned laminated body on which the laser image was recorded was removed from the drum and the image receiving sheet and the image recording transfer sheet were peeled off by hand, the image (image line) forming layer was formed. Only the laser irradiation part was transferred from the transfer sheet to the image receiving sheet with a recording line width of 5.0 μm. (7) Formation of Retransfer Image An image receiving sheet on which a color image was formed as described above was superposed on art paper, and a retransfer color image was formed on the art paper in the same manner as in Example 1.

[0076]

[Table 3] Table 3 ──────────────────────────────────── Amorphous organic polymer (Used amount: g) Chlorinated polypropylene PVC / vinyl acetate copolymer Polyvinyl Product name Used amount Product name Used amount Butyral ───────────────────────── ──────────── Sample 7 Super Clone 2.4 None 9.6 106H Sample 8 Super Clone 6.0 None 6.0 6.0 H Sample 9 Super Clone 9.8 None 2.2 106H Sample 10 None MPR-TMF 2.4 9.6 Sample 11 None MPR-TMF 6.0 6.0 Sample 12 None MPR-TMF 9.6 2.4 ────────────────── ──────────────────── Control sample 2 None None 12.0 ──────────────────────────────────── Chlorinated polypropylene resin: Super Clone 106H (Japan Vinyl chloride / vinyl acetate copolymer: MPR-TMF (manufactured by Nisshin Chemical Co., Ltd.) (Vinyl chloride: vinyl acetate: other = 90: 7: 3) Polyvinyl butyral: Denka butyral # 2000- L (manufactured by Denki Kagaku Kogyo Co., Ltd.)

[Image Evaluation by Image Formation Using Laser Light] With respect to various color retransfer images obtained as described above, the dot quality (dot shape, halftone dot% by the same method as in Example 1 was used. ), And printed matter closeness. The optical reflection densities on the obtained monochromatic art papers were almost the same values as in the case of Example 1 above. The results are shown in Table 4.

[0078]

[Table 4] Table 4 ──────────────────────────────────── Ink layer dot quality Self-supporting Shape Minimum dot network% Similarity to printed matter ──────────────────────────────────── Sample 7 None BB 4% BB Sample 8 None AA 4% BB Sample 9 None AA 3% AA Sample 10 None BB 5% BB Sample 11 None BB 4% BB Sample 12 None AA 3% BB ─────────────── ────────────────────── Control sample 2 Yes DD 9% CC ──────────────────── ──────────────── Evaluation was performed by the following relative evaluation. However, the color image obtained by using the comparative sample 2 was evaluated based on the following criteria (based on DD for dot shape, and CC for printed material similarity). AA: Very good compared to the control. BB: Good compared with the comparative control.

From the results in Table 4 above, by using the heat-sensitive transfer sheet according to the present invention in which the ink layer is very fragile, a transferred image with good dot quality can be obtained even when image formation using laser light is carried out. It is clear that the transferred image is excellent in printed matter approximation.

[0080]

EFFECT OF THE INVENTION By using the heat-sensitive transfer sheet having the brittle ink layer of the present invention, only the area gradation can be obtained.
The dot shape including the edge sharpness of the image, the dot quality such as the dot% of the minimum limit of reproducibility, etc. are improved,
Further, it is possible to obtain a transferred image having excellent printed matter approximation. Therefore, it is possible to obtain a good retransfer image which is advantageous for color proof use and the like.

[Brief description of drawings]

FIG. 1 is a graph showing a particle size distribution of a cyan pigment used in Example 1. The horizontal axis of the graph represents the particle size (μm), the left vertical axis represents the percentage of particles of each particle size, and the right vertical axis represents the cumulative percentage.

2 is a graph showing the particle size distribution of the magenta pigment used in Example 1. FIG. The method of displaying the graph is the same as in FIG.

3 is a graph showing the particle size distribution of the yellow pigment used in Example 1. FIG. The method of displaying the graph is the same as in FIG.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location 7416-2H B41M 5/26 Q

Claims (7)

[Claims] 1. A pigment and an amorphous organic high-molecular polymer each having a softening point in the temperature range of 40 ° C. to 150 ° C.
.About.70 wt%, and 25 to 65 wt%, and a layer thickness of 0.
It has an ink layer in the range of 2 μm to 1.0 μm, and the constituent material of the ink layer is 200 μm in film thickness, 3 cm × 5 c
A heat-sensitive transfer sheet made of a material that does not have self-supporting properties when formed into a sheet having a size of m. 2. The heat-sensitive transfer sheet according to claim 1, wherein 70% by weight or more of the pigment in the ink layer has a particle size of 0.1 to 1.0 μm. 3. The amorphous organic high molecular polymer is 10 to 90.
The heat-sensitive transfer sheet according to claim 1, wherein the heat-sensitive transfer sheet is a mixture of an amorphous chlorinated polyolefin resin or a vinyl chloride / vinyl acetate copolymer in a weight% and the remaining amount of other amorphous organic polymer. 4. The amorphous organic high molecular polymer is 10 to 90.
The heat-sensitive transfer sheet according to claim 1, which is a mixture of amorphous chlorinated polyolefin resin or vinyl chloride / vinyl acetate copolymer in an amount of 90% by weight and polyvinyl butyral in an amount of 90 to 10% by weight. 5. A transfer image formed by overlaying an image receiving sheet on the ink layer of the heat-sensitive transfer sheet according to claim 1, pressing a thermal head from the back of the heat-sensitive transfer sheet, and forming an area gradation on the image receiving sheet. And then the transferred image on the image-receiving sheet is re-transferred onto a separately prepared white support, and an optical reflection density of 1.0 or more is formed on the white support. Forming a transfer image. 6. An image receiving sheet is superposed on the ink layer of the heat-sensitive transfer sheet according to claim 1, and a laser beam modulated by a digital signal is irradiated from the back surface of the heat-sensitive transfer sheet to give an optical reflection density on the image-receiving sheet. An image forming method comprising forming a transfer image having an area gradation of 1.0 or more. 7. The image-receiving sheet is superposed on the ink layer of the heat-sensitive transfer sheet according to claim 1, and a laser beam modulated by a digital signal is irradiated from the back surface of the heat-sensitive transfer sheet, and the image-receiving sheet is then subjected to an ablation method. An image forming method, which comprises forming a transfer image having an area gradation with an optical reflection density of 1.0 or more.